Solar cells for direct conversion of incident sunlight into electrical energy are commercially produced at the present time by a number of companies including General Electric Co., Laser Diode Inc., and Spectrolab Division of Hughes Aircraft Co.
Until recently, utilization of solar cells to provide electrical energy for local consumption (e.g., for supplementing the supply of electrical energy to a building) has generally occurred only on an experimental or demonstration basis. However, significant improvements are continually being made in the efficiency and also in the cost of manufacturing solar cells. Recent studies indicate that in the present state of technology the economic value of electrical energy that can be supplied to a building by an array of solar cells of the photovoltaic type over a specified time period now exceeds the "recovery cost" over that time period allocable to the manufacture of such solar cells. Nevertheless, before widespread adoption of solar cell technology in building construction and renovation can become economically feasible, it will be necessary to develop standardized techniques for integrating networked arrays of solar cells into the designs of new buildings to be constructed, and for retrofitting arrays of solar cells into existing buildings.